1. Field of the Invention
The invention relates to a living hinge. Such hinges are also known as live or flexible hinges in the art.
2. Description of the Related Art
Common articulating hinges are relatively complex, expensive, multipart devices with separate parts for rotating attachment edges about a pivot or axis. Living or live hinges are relatively simpler, lower-cost, one-piece flexing devices or functional hinges having of a flexing zone between attachment edges.
A living hinge of high strength requires the desirable qualities of toughness and stability found in metal or other high strength materials. However, those same properties of strength and rigidity limit their flexibility to be used as living hinges.
U.S. Pat. No. 6,355,335 to Kulkaski discloses a flexible hinge having a thin flexible web between two inflexible members. U.S. Pat. No. 4,619,304 to Smith teaches a hinged structure having S-shaped hinge members of resiliently flexible material passing partially around each other and tensioned around supports. Both the Kulkaski and Smith devices have extremely complicated, multipart configurations.
U.S. Pat. No. 4,236,273 to McCaffrey relates to a spring-like hinge in which a spring-like compressive force is applied to arcuate arms. The McCaffrey device relies upon the inherent flexibility of the material of the arms. However, that flexibility reduces and limits hinge strength and flexing cycle life.
U.S. Pat. No. 4,660,418 to Greenwood et al. discloses a flexible hinge in which a groove portion is etched away in a silicon body. The opposing surfaces of the hinge are placed alternately in destructive tension and compression, leading to low cycle life durability and high failure rates due to molecular disruption and fracture in the area of tension.